title: Alkalosis-induced coronary vasoconstriction: effects of calcium, diltiazem, nitroglycerin, and propranolol.
abstract: We examined the effects of changes in pH, Ca2+ concentration, diltiazem, nitroglycerin, and propranolol on the vascular tone of the isolated rabbit coronary artery. Stepwise increase in pH of the bath fluid caused pH-dependent increased vascular tone. Increase in Ca2+ concentration of the bath fluid also resulted in increased vascular tone, while removal of Ca2+ abolished the high pH-induced elevated vascular tone. Diltiazem and nitroglycerin suppressed the high pH-induced increased vascular tone. Propranolol in high concentrations exhibited a direct inhibitory effect on the high pH-induced increased vascular tone. We conclude that high pH induces coronary vasoconstriction principally by increasing transmembrane influx of Ca2+ and that diltiazem and nitroglycerin suppress this action.
mesh_terms: D000471:Alkalosis / Q000503:physiopathology*; D000818:Animals; D001552:Benzazepines / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology*; D003331:Coronary Vessels / Q000187:drug effects* / Q000503:physiopathology; D004110:Diltiazem / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006863:Hydrogen-Ion Concentration; D005996:Nitroglycerin / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology*; D011817:Rabbits
chemical_list: D001552:Benzazepines; D011433:Propranolol; D004110:Diltiazem; D005996:Nitroglycerin; D002118:Calcium